Of course it is. He swore to protect and uphold the Constitution. That's a solemn oath.
That's the job of the legislature.
In MA, the legislature HAD checked the out of control "Goodridge" court. They ignored them. If Romney had simply ignored them too, the legislative and the executive branches would have checked these four out-of-control leftist judges. But no, Romney saw fit to side with the lawless decision of the court and joined them in checking the legislature. "Stroke of the pen, law of the land. Pretty cool!" But, there is still no law.
This is a childish interpretation. There is such a thing as areas of authority, jurisdiction, etc.
If I'm the Governor of, say, North Dakota, and I think the Constitution is being violated in Nebraska, what should I do?
Answer: Nothing more then a normal citizen. It's not in my area of authority.
In the same way, Governors shouldn't 'protect' the Constitution by violating the separation of powers set up by that same Constitution.
I've proven your idiocy about the Mass. Legislature wrong so many times, as have others, I'm not even going to bother again.